System, method, and computer-readable medium for mobile terminated call processing by a femtocell system

ABSTRACT

A system, method, and computer readable medium for processing a call setup in a network system are provided. A femtocell system receives a call origination for a call to be terminated with a user equipment serviced by the femtocell system from a core network, transmits a page message to the user equipment, performs a service connection with the user equipment, creates a connection for the core network, and completes the call setup with the user equipment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of U.S. patentapplication Ser. No. 12/252,234 entitled SYSTEM, METHOD, ANDCOMPUTER-READABLE MEDIUM FOR MOBILE TERMINATED CALL PROCESSING BY AFEMTOCELL SYSTEM filed Oct. 15, 2008, now U.S. Pat. No. 8,059,585 whichclaims priority to U.S. provisional patent application Ser. No.60/936,626 entitled FEMTOCELL filed Jun. 21, 2007, and claims priorityto U.S. provisional patent application Ser. No. 61/003,151 entitledSIP-IOS ADAPTER FUNCTION filed Nov. 15, 2007, the disclosure of each ofwhich is incorporated in its entirety herein by reference.

FIELD OF THE INVENTION

The present invention is generally related to radio access technologiesand, more particularly, to mechanisms for processing call originationsin a network system.

BACKGROUND OF THE INVENTION

Contemporary cellular radio systems, or mobile telecommunicationsystems, provide an over-the-air interface to wireless user equipments(UEs) via a radio access network (RAN) that interfaces with at least onecore network. The RAN may be implemented as, for example, a CDMA2000RAN, a Universal Mobile Telecommunications System (UMTS) RAN, a GlobalSystem for Mobile communications (GSM) RAN, or another suitable radioaccess network implementation. A UE may comprise, for example, a mobileterminal such as a mobile telephone, a laptop computer featuring mobiletelephony software and hardware, a personal digital assistant (PDA), orother suitable equipment adapted to transfer and receive voice or datacommunications with the radio access network.

A RAN covers a geographical area comprised of any number of cells eachcomprising a relatively small geographic area of radio coverage. Eachcell is provisioned by a cell site that includes a radio tower, e.g., abase transceiver station (BTS), and associated equipment. BTSscommunicate with UEs over an air interface within radio range of theBTSs.

Numerous BTSs in the RAN may be communicatively coupled to a basestation controller, also commonly referred to as a radio networkcontroller (RNC). The BSC manages and monitors various system activitiesof the BTSs serviced thereby. BSCs are coupled with at least one corenetwork.

BTSs are typically deployed by a carrier network in areas having a highpopulation density. The traffic capacity of a cell site is limited bythe site's capacity and affects the spacing of cell sites. In suburbanareas, sites are often up to two miles apart, while cell sites deployedin dense urban areas may be as close as one-quarter of a mile apart.Because the traffic capacity of a cell site is finitely limited, as isthe available frequency spectrum, mobile operators have a vestedinterest in technologies that allow for increased subscriber capacity.

A microcell site comprises a cell in a mobile phone network that coversa limited geographic area, such as a shopping center, hotel, airport, orother infrastructure that may have a high density mobile phone usage. Amicrocell typically uses power control to limit the radius of themicrocell coverage. Typically a microcell is less than a mile wide.

Although microcells are effective for adding network capacity in areaswith high mobile telephone usage, microcells extensively rely on theRAN, e.g., a controlling BSC and other carrier functions. Becausecontemporary BSCs have limited processing and interface capacity, thenumber of BTSs—whether microcell BTSs or typical carrier BTSs—able to besupported by the BSC or other RAN functions is disadvantageouslylimited.

Contemporary interest exists in providing small office/home office(SOHO) radio access by an even smaller scale BTS. The radio coveragearea of such a system is typically referred to as a femtocell. In asystem featuring a femtocell, a UE may be authorized to operate in thefemtocell when proximate the femtocell system, e.g., while the UE islocated in the SOHO. When the UE moves beyond the coverage area of thefemtocell, the UE may then be serviced by the carrier network. Theadvantages of deployment of femtocells are numerous. For instance,mobile users frequently spend large amounts of time located at, forexample, home, and many such users rely extensively on cellular networkservice for telecommunication services during these times. For example,a recent survey indicated that nearly thirteen percent of U.S. cellphone customers do not have a landline telephone and rely solely on cellphones for receiving telephone service. From a carrier perspective, itwould be advantageous to have telephone services provisioned over afemtocell system, e.g., deployed in the user's home, to thereby reducethe load, and effectively increase the capacity, on the carrier RANinfrastructure. However, various issues related to processing calloriginations and terminations in such a system remain unresolved.

Therefore, what is needed is a mechanism that overcomes the describedproblems and limitations.

SUMMARY OF THE INVENTION

The present invention provides a system, method, and computer readablemedium for call processing by a femtocell system in a network system. Acommunication system features an IP-based femtocell system forprovisioning communication services to a user equipment. In oneimplementation, the femtocell system includes a base transceiverstation, a transcoder, and a Session Initiation Protocol to InternetOperating System adapter. The femtocell system may receive an INVITEmessage from a core network for a call to be terminated with a userequipment serviced by the femtocell system. The femtocell system maypage the user equipment, and the Session Initiation Protocol to InternetOperating System adapter may transmit a connection request to thetranscoder which, in turn, opens a real time transport protocol portwith a service mode of receive only. An assignment request istransmitted from the Session Initiation Protocol to Internet OperatingSystem adapter to the base transceiver station. In response, the basetransceiver station transmits a channel assignment and a service connectmessage to the user equipment. In response to receiving a serviceconnect completion message, the femtocell system transmits a ringingindication to the core network and may modify the service mode of thetranscoder to send and receive. A bearer is then established for thecall, and an alert is transmitted to the user equipment. In response toreceiving a connect order from the user equipment, the call setup iscompleted by the femtocell system.

In one embodiment of the disclosure, a method of processing a call setupin a network system is provided. The method includes receiving, by afemtocell system, a call origination for a call to be terminated with auser equipment serviced by the femtocell system from a core network,transmitting, by the femtocell system, a page message to the userequipment, performing, by the femtocell system, a service connectionwith the user equipment, creating, by the femtocell system, a connectionfor the core network, and completing the call setup with the userequipment.

In a further embodiment of the disclosure, a computer-readable mediumhaving computer-executable instructions for execution by a processingsystem, the computer-executable instructions for processing a call setupin a network system is provided. The computer-readable medium comprisesinstructions that receive, by a femtocell system, a call origination fora call to be terminated with a user equipment serviced by the femtocellsystem from a core network, transmit, by the femtocell system, a pagemessage to the user equipment, transmit, by a Session InitiationProtocol to Internet Operating System adapter of the femtocell system, acreate connection message to a transcoder of the femtocell system,perform, by the femtocell system, a service connection with the userequipment, create, by the femtocell system, a connection for the corenetwork, and complete the call setup with the user equipment.

In a further embodiment of the disclosure, a system for processing acall setup in a network system is provided. The system includes apacket-switched network, an Internet Protocol Multimedia subsystemcommunicatively coupled with the packet-switched network, and afemtocell system communicatively coupled with the packet-switchednetwork. The femtocell system includes a base transceiver station, atranscoder, and a Session Initiation Protocol to Internet OperatingSystem adapter. The femtocell system receives a call origination for acall to be terminated with a user equipment serviced by the femtocellsystem from the Internet Protocol Multimedia subsystem, and transmits apage message to the user equipment. The Session Initiation Protocol toInternet Operating System adapter transmits a create connection messageto the transcoder and the transcoder opens at least one real timetransport protocol port in response thereto. The femtocell systemperforms a service connection with the user equipment, creates aconnection for the Internet Protocol Multimedia subsystem, and completesthe call setup with the user equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures, in which:

FIG. 1 is a diagrammatic representation of a network system thatincludes a cellular network adapted to provide macro-cellular coverage;

FIG. 2 is a diagrammatic representation of a conventional network systemconfiguration featuring a femtocell;

FIG. 3 is a diagrammatic representation of a network system in which afemtocell system implemented in accordance with an embodiment of thepresent invention may be deployed;

FIG. 4 is a simplified diagrammatic representation of the femtocellsystem depicted in FIG. 3 that may be connected with an IP backhaul inaccordance with an embodiment;

FIG. 5 is a diagrammatic representation of an exemplary sessioninitiation protocol registration message generated by a femtocell systemon behalf of a user equipment in accordance with an embodiment;

FIG. 6 is a diagrammatic representation of a network system featuring afemtocell network implemented in accordance with an embodiment;

FIG. 7 is a flowchart that depicts a femtocell system call processingroutine that facilitates mobile terminated call processing implementedin accordance with an embodiment; and

FIGS. 8A and 8B show a diagrammatic representation of a signaling flowfor a mobile terminated call processing routine implemented inaccordance with an embodiment

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the following disclosure provides manydifferent embodiments or examples for implementing different features ofvarious embodiments. Specific examples of components and arrangementsare described below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting.

FIG. 1 is a diagrammatic representation of a network system 100 thatincludes a cellular network 110 adapted to provide macro-cellularcoverage to a user equipment. Cellular network 110 may comprise, forexample, a code-division multiple access (CDMA) network, such as aCDMA-2000 network.

Cellular network 110 may include any number of base transceiver stations(BTSs) 112 a-112 c communicatively coupled with a base stationcontroller (BSC) 114 or RNC. Each individual BTS 112 a-112 c under thecontrol of a given BSC may define a radio cell operating on a set ofradio channels thereby providing service to a user equipment (UE) 125,such as a mobile terminal. BSC 114 manages the allocation of radiochannels, receives measurements from mobile terminals, controlshandovers, as well as various other functions as is understood. BSC 114is interconnected with a mobile services switching center (MSC) 116 thatprovides mobile terminal exchange services. BSC 114 may be additionallycoupled with a packet data serving node (PDSN) 118 or other gatewayservice that provides a connection point between the CDMA radio accessnetwork and a packet network, such as Internet 160, and providesmobility management functions and packet routing services. MSC 116 maycommunicatively interface with a circuit switched network, such as thepublic switched telephone network (PSTN) 150, and may additionally becommunicatively coupled with an interworking function (IWF) 122 thatprovides an interface between cellular network 110 and PSTN 150.

System 100 may also include a signaling system, such as a signalingsystem #7 (SS7) network 170. SS7 network 170 provides a set of telephonysignaling protocols which are used to set up the vast majority of theworld's PSTN telephone calls. SS7 network 170 is also used in cellularnetworks for circuit switched voice and packet-switched dataapplications. As is understood, SS7 network 170 includes varioussignaling nodes, such as any number of service control points (SCPs)172, signal transfer points (STPs) 174, and service switching points(SSPs) 176.

BTSs 112 a-112 c deployed in cellular network 110 may service numerousnetwork 110 subscribers. Cell cites provided by BTSs 112 a-112 ccommonly feature site ranges of a quarter to a half mile, e.g., indensely populated urban areas, to one to two miles in suburban areas. Inother remotely populated regions with suitable geography, site rangesmay span tens of miles and may be effectively limited in size by thelimited transmission distance of relatively low-powered UEs. As referredto herein, a cell provided by a BTS deployed in carrier network 110 foraccess by any authorized network 110 subscriber is referred to as amacrocell.

FIG. 2 is a diagrammatic representation of a conventional network system200 configuration featuring a femtocell. In the depicted example, acentral BSC 214 deployed in a cellular carrier network 210 may connectwith a soft switch core 212 that is connected with a MSC 216. MSC 216connects with the cellular core network and may interface with othernetworks, such as the PSTN as is understood. BSC 214 may be connectedwith and service numerous BTSs 212 a-212 c that provide macrocells tocellular network 210 subscribers.

BSC 214 may additionally connect with a tunnel gateway system 218 thatis adapted to establish secured tunnels 232 a-232 x with respectivefemtocell systems 250 a-250 x. Femtocells comprise cellular accesspoints that connect to a mobile operator's network using, for example, aresidential DSL or cable broadband connection. Femtocells 250 a-250 xprovide a radio access point for UE 225 when the UE is within range of afemtocell system with which the UE has authorized access. For example,femtocell system 250 a may be deployed in a residence of the user of UE225. Accordingly, when the user is within the residence, mobiletelecommunications may be provided to UE 225 via an air-interfaceprovided by femtocell system 250 a. In this instance, UE 225 iseffectively offloaded from the macro BTS, e.g., BTS 212 a, andcommunications to and from the UE are carried out with femtocell system250 a over Internet 260. Thus, femtocell systems 250 a-250 x may reducethe radio resource demands by offloading UEs from macrocells tofemtocells and thereby provide for increased subscriber capacity ofcellular network 210.

In contemporary implementations such as that depicted in FIG. 2, afemtocell system 250 a comprises a transceiver without intelligence andis thus required to be connected and managed by BSC 214. Thus, femtocellsystems 250 a-250 x are reliant on the carrier network centralized BSC214 which has limited capacity and thus does not exhibit desirablescaling characteristics or capabilities. Moreover, high communicationsoverhead are realized by the BTS backhaul.

FIG. 3 is a diagrammatic representation of a network system 300 in whicha femtocell system implemented in accordance with an embodiment of theinvention may be deployed. System 300 includes a radio access network(RAN) 310 that provides an over-the-air interface with a UE 325, e.g., amobile terminal. RAN 310 may comprise, for example, a CDMA radio accessnetwork or another suitable RAN. RAN 310 may comprise various BTSs andassociated base station controllers BSCs as well as other infrastructureas is understood. UE 325 may be implemented as a personal digitalassistant (PDA), a mobile phone, a computer, or another device adaptedto interface with RAN 310.

System 300 may include an IP Multimedia Subsystem (IMS) 320 architectureadapted to provide IP service to UE 325. To this end, RAN 310 iscommunicatively coupled with a serving general packet radio service(GPRS) support node (SGSN) 314 and a gateway GPRS support node (GGSN)316. SGSN 314 provides the delivery of data packets from and to UE 325within its service area. GGSN 316 provides an interface between the GPRSbackbone network and external packet data networks. GGSN 316 iscommunicatively coupled with a policy decision function (PDF) 318 thatprovides authorization of media plane resources, e.g., quality ofservice (QoS) authorizations, policy control, bandwidth management, andthe like. PDF 318 may be communicatively coupled with a call sessioncontrol function (CSCF) 320.

CSCF 320 comprises various session initiation protocol (SIP) servers orproxies that process SIP signaling packets in IMS 320. CSCF 320 mayinclude a proxy-CSCF (P-CSCF) that provides a first point of contact foran IMS-compliant UE. The P-CSCF may be located in the visited network,or in the UE's home network if the visited network is not fullyIMS-compliant. UE 325 may discover the P-CSCF, e.g., by using DynamicHost Configuration Protocol (DHCP), or by assignment in a packet dataprotocol (PDP) context. CSCF 320 additionally includes a Serving-CSCF(S-CSCF) that comprises the central node of the signaling plane. TheS-CSCF comprises a SIP server, but additionally performs sessioncontrol. The S-CSCF is located in the home network and interfaces with ahome subscriber server (HSS) 340 to download and upload user profiles.CSCF 320 further includes an Interrogating-CSCF (I-CSCF) that comprisesa SIP function located at the edge of an administrative domain. TheI-CSCF has an IP address that is published in the Domain Name System(DNS) 372 that facilitates location of the I-CSCF by remote servers.Thus, the I-CSCF is used as a forwarding point for receipt of SIPpackets within the domain.

HSS 340 comprises a user database that supports the IMS network entitiesthat manage calls. HSS 340 stores user profiles that specifysubscription-related information of authorized users, authenticates andauthorizes users, and provides information about the user's physicallocation. Various application servers (AS) 342 a-342 n that host andexecute services interface with CSCF 320 via SIP.

CSCF 320 is coupled with a breakout gateway control function (BGCF) 322that comprises a SIP server that provides routing functionality based ontelephone numbers. BGCF 322 is used when a UE places a call from the IMSto a phone in a circuit switched network, e.g., PSTN 330, or the publicland mobile network. A media gateway controller Function (MGCF) 324performs call control protocol conversion between SIP and ISDN User Part(ISUP) and interfaces with a signaling gateway (SGW) 326. SGW 326interfaces with the signaling plane of a circuit switched network, e.g.,PSTN 330. SGW 326 may transform lower layer protocols, such as StreamControl Transmission Protocol (SCTP), into the Message Transfer Part(MTP) protocol, and pass ISUP data from MGCF 324 to PSTN 330 or anothercircuit switched network. A media gateway (MGW) 328 interfaces with themedia plane of PSTN 330 or another circuit switched network byconverting data between real-time transport protocol (RTP) and pulsecode modulation (PCM), and may also be employed for transcoding when thecodecs of the IMS and circuit switched networks differ. Resources of MGW328 are controlled by MGCF 324. Fixed access, e.g., IP telephony devices374 a-374 b, may connect with IMS network via Internet 370 that iscommunicatively coupled with IMS network 320 by way of border gateway360.

As is understood, DNS 372 comprises a scalable namespace thatfacilitates access to entities deployed on the Internet or privatenetworks. DNS 372 maintains various records for host names, servers, andthe like. For example, DNS 372 maintains records (commonly referred toas “A records”) that map hostnames to IP addresses, pointer (PTR)records that map IP addresses to canonical names to facilitate reverseDNS lookups, service (SRV) records that specify information on availableservices, naming authority pointer (NAPTR) records that facilitateregular expression based rewriting, and various other records. DNS 372may additionally include a telephone number mapping (ENUM) system thatfacilitates resolution of SIP addresses from E.164 number as isunderstood.

A base station manager (BSM) 378 may be deployed in Internet 370 and maybe adapted to communicate with numerous femtocell systems and femtocellnetworks. BSM 378 may provide various operations, maintenance, andmanagement functions to femtocell systems. For example, BSM 378 mayprovide service provisioning of femtocell systems, e.g., by providingconfiguration downloads to femtocell systems and preloading defaultconfiguration data for femtocell systems distributed via sales channels.BSM 378 may provide various support and maintenance features, such asalarm and periodic statistics reporting, automatic remote software imagedistribution to femtocell systems, provide upgrades andreconfigurations, and may provide remote access via Internet 370 fordiagnostics and customer support.

In accordance with an embodiment, a femtocell system 350 may includeintegrated BTS and BSC functions and may feature additional capabilitiesavailable in the provided femtocell site coverage area. Femtocell system350 provides an IP-accessible radio access network, is adapted foroperation with IMS 320, and provides radio link control functions.Femtocell system 350 may be communicatively coupled with Internet 370via any variety of backhaul technologies, such as an 802.11x link, a10/100 BaseT LAN link, a T1/E1 Span or fiber, cable set top box, DSLmodem connected with a central office digital subscriber line accessmultiplexer, a very small aperture terminal (VSAT), or another suitablebackhaul infrastructure.

Femtocell system 350 may include a session initiation protocol (SIP)adapter that supports a SIP client pool and provides conversion of callset-up functions to SIP client set-up functions. For example, a SIPclient pool allocated by femtocell system 350 may comprise a pluralityof SIP user agents 352 a-352 c that each may be allocated for a UEauthorized to access femtocell system 350. Additionally, femtocellsystem 350 includes electronic serial number (ESN) screening to allowonly designated UEs to access the femtocell thereby restricting accessto authorized home or small office UEs. For example, femtocell system350 may be configured with an ESN list 354 that specifies ESNs of UEsauthorized to access femtocell system 350. In the illustrative example,ESNs of “ESN 1”-“ESN 3” are included in ESN list 354. Provisioning ofESN(s) may be made as part of an initial femtocell system 350activation. In the illustrative example, femtocell system 350 isallocated an Internet Protocol (IP) address of “66.249.73.42”, and UE325 is allocated a mobile services ISDN (MSISDN) number, or E.164number, of “12145551212”.

FIG. 4 is a simplified diagrammatic representation of femtocell system350 depicted in FIG. 3 that facilitates provisioning of a femto-RAN inaccordance with an embodiment. Femtocell system 350 includes an antenna400 coupled with a BTS 410. BTS 410 may be implemented, for example, asa 1xRTT ASIC device and may comprise a non-diversity receiver featuringa built-in duplexer. In an embodiment, BTS 410 may feature only oneoperational band and may include a transmitter scan receiver and localoscillator. BTS 410 may be communicatively coupled with a BSC 420 thatprovides radio control functions, such as receiving measurements fromUEs, such as mobile phones, control of handovers to and from otherfemtocell systems, and may additionally facilitate handoff to or frommacrocells.

Femtocell system 350 includes an electronic serial number screeningfunction 430 that may facilitate approving or rejecting service for a UEby femtocell system 350. Femtocell system 350 includes a transcoder 440and an Internet Operating System (IOS) and SIP Adapter (collectivelyreferred to as IOS-SIP Adapter 450). IOS-SIP adapter 450 may invoke andmanage SIP clients, such as a user agent (UA) pool comprising one ormore UAs. In accordance with an embodiment, each UE 325 authorized to beserviced by femtocell system 350 may have a UA allocated therefor byfemtocell system in a manner that facilitates transmission ofcommunications to and from a UE over an IP backhaul. Accordingly, whenan authorized UE is within the femtocell system 350 site range,telecommunication services may be provided to the UE via the IP backhauland femtocell system 350 provisioned RAN. When the UE is moved beyondthe service range of femtocell system 350, telecommunication service maythen be provided to the UE via macrocellular coverage.

To facilitate routing of calls from circuit switched call originators,femtocell system 350 may perform a DNS/ENUM registration on behalf ofUEs authorized to obtain service from femtocell system 350. In thepresent example, assume UE 325 with a MSISDN of “12145551212” has a SIPservice subscription in the domain “example.com” and has a SIP uniformresource identifier (URI) of “12145551212@example.com”. An exampleDNS/ENUM registration message generated by femtocell system 350 onbehalf of UE 325 and transmitted to DNS 372 is as follows:

$ORIGIN 2.1.2.1.5.5.5.4.1.2.1.e164.arpa.

IN NAPTR 100 10 “u” “E2U+sip” “!^.*Vsip:12145551212@example.com!”.

As is understood, the first line of the registration message comprisesthe MSISDN number of the UE converted (i.e., reversed with each numeraldelineated with a “.” character and appended with the e164.arpa domain)for DNS lookup. The second line of the registration message specifiesthe NAPTR record for the hosts that can further process the address—thedomain “example.com” (in which the UE with a URI of12145551212@example.com is registered) in the present example.

Femtocell system 350 may generate and issue a SIP registration on behalfof UE 325 authorized for service access by femtocell system 350. FIG. 5is a diagrammatic representation of an exemplary SIP registrationmessage 500 generated by femtocell system 350 on behalf of UE 325authorized for service access thereby in accordance with an embodiment.Registration message 500 may be transmitted from femtocell system 350 toa location service, such as a SIP registrar implemented as SIP Registrar380. Registrar 380 may provide the location and contact information tolocation service 382. Registration message 500 includes a REGISTER field510 that specifies the registration is being made within the domain“example.com”. Multiple contacts may be included in registration message500. In the present example, registration message 500 includes a contactfield 512 that specifies a SIP contact for UE 325. Notably, the SIPcontact field 512 for UE 325 specifies the UA registered on behalf of UEwith the URI 12145551212@exmaple.com is located at the IP address of“66.249.73.42”. That is, the SIP contact registered by femtocell system350 on behalf of UE 325 is to be addressed at the femtocell system 350address of 66.249.73.42 thereby resulting in routing of SIP signalingmessages to femtocell system 325. In turn, femtocell system 350 mayconvert SIP call set up messaging to RAN signaling, allocate an uplinkand a downlink channel for UE 325, and set up a call or data sessionthereon.

In the present example, registration message 500 includes a secondcontact field 514 that specifies a telephone URI, e.g., theMSISDN+1-214-555-1212 of UE 325. Thus, a location query for the SIP URIsip:12145551212@example.com would return two contacts. The first is theSIP URI that can be used to reach femtocell system 350, and thus UE 325thereby, and the second is the telephone URI that can be used to reachUE 325 via macrocellular coverage, i.e., via RAN 310. As is understood,the order of contacts 512-514 provides a contact preference, and themultiple contacts may be registered in separate registration messages.The depicted registration message including both the SIP contact URI andtelephone URI is exemplary only. Accordingly, in the present example, anattempt to contact UE 325 may first be made via the SIP URI12145551212@example.com. In the event that the session is notsuccessfully set up via the SIP contact, an attempt may be made to setupa session via RAN 310 using the telephone URI.

When the UE 325 moves outside the coverage area of femtocell system 350,another registration may be generated and submitted by femtocell system350 on behalf of UE 325 where the telephone URI is designated as thepreferred contact. Further, the SIP URI may be removed from theregistration when the UE 325 moves outside the coverage area offemtocell system 350 thereby avoiding any attempts to establish asession with UE 325 via femtocell system 350 when UE 325 has movedbeyond the femtocell system 350 coverage area.

To better facilitate an understanding of disclosed embodiments, considera call placed at circuit switched telephone 332 to UE 325. A gatewayreceives the call setup request, e.g., an Initial Address Message (IAM),and a query may be made with DNS 372 from which the domain “example.com”is resolved from the ENUM function. An INVITE message is thentransmitted to the example.com domain which, in turn, resolves thelocation of the called UE 325. Particularly, CSCF 320 may interrogatelocation server 382 and determine UE 325 is registered as located at theIP address 66.249.73.42. Accordingly, the INVITE message is routed toproxy server 376 which forwards the INVITE message to femtocell system350. Femtocell system 350 may then perform paging, channel allocation,and other procedures for provisioning a radio interface with UE 325 andissue SIP responses on behalf of UE 325. Thus, from a networkperspective, femtocell system 350 appears as a user agent to which thecall is directed. Further, UE 325 does not require a SIP client forreceiving the call because femtocell system 350 advantageously performssignaling and media conversion for signaling and media transmissionsover-the-air interface with 325. Thus, femtocell system 350 may appearas a conventional BTS to UE 325. A call from UE 325 to another terminal,such as circuit-switched telephone 332, a SIP client such aspacket-switched telephony device 374 a, or another device, may similarlybe facilitated by femtocell system 350.

As a second example, assume UE 325 has moved beyond the range offemtocell system 350. As noted above, femtocell system 350 may generateand transmit a registration message that excludes the SIP contact tofacilitate provisioning of telecommunication services via macrocellcoverage, e.g., via RAN 310. For instance, femtocell system 350 mayperiodically perform power measurements with UE 325, and upon the powermeasurement dropping below a particular power threshold, femtocellsystem may determine UE 325 is to be serviced by macrocellular coverage.Alternatively, a user may select macrocellular coverage via a userinterface provided on UE 325. In this instance, UE 325 may provide anindication to femtocell system 350 that telecommunication services areto be provided by RAN 310. Other scenarios may similarly result in adetermination that UE 325 is to be serviced by RAN 310. Upon such adetermination, femtocell system 350 may generate and transmit aregistration message on behalf of UE 325 to a registrar service, e.g.,CSCF 320 and SIP registrar 380. The contact information may then beupdated in location server 382 to indicate the telephone URI as thecontact of UE 325. In this scenario, consider a call placed at circuitswitched telephone 332 to UE 325. A gateway receives the call setuprequest, e.g., an Initial Address Message (IAM), and a query may be madewith DNS server 372 from which the domain “example.com” is resolved fromthe ENUM service. An INVITE message is then transmitted to theexample.com domain which resolves the location of called UE 325. In thepresent example, CSCF 320 may interrogate location server 382 anddetermine UE 325 has a preferred contact registered as a telephone URIof 2145551212. Accordingly, the INVITE message is routed to a gatewayserver, e.g., gateway server 390 which translates the INVITE message toa RAN-compliant call request signaling. The call may then be setup viaRAN 310 accordingly.

A network of femtocell systems may be deployed and connected with an IPbackhaul. In this implementation, an authorized UE may be serviced bythe femtocell network, and service may be transferred from one femtocellto another femtocell via a femtocell handoff procedure. In the eventthat the femtocell network is deployed in an area serviced by amacrocellular network, handoff routines may provide preference fortransferring a UE to a target femtocell system rather than a macrocellsite. In the event that a suitable femtocell is unavailable for handoffof a UE, the UE may be transferred to the macrocell site.

FIG. 6 is a diagrammatic representation of a network system 600featuring a femtocell network implemented in accordance with anembodiment of the invention. System 600 includes a RAN 610 that providesan over-the-air interface with UEs 625 a-625 c, e.g., a mobile terminal.RAN 610 may comprise, for example, a CDMA radio access network oranother suitable RAN. RAN 610 may comprise various BTSs 612 a-612 c andassociated BSCs 604 as well as other infrastructure as is understood.Each of BTSs 612 a-612 c provide a respective macrocell 602 a-602 c thatmay provide telecommunication service to UEs 625 a-625 c. BSC 604 iscoupled with a MSC 606 that provides cellular exchange services,mobility management, and other services within the area that it servesas is understood.

RAN 610 may interface with IMS 620 adapted to provide IP service to UEs625 a-625 c. To this end, RAN 610 may be communicatively coupled with aSGSN 614 and a GGSN 616. GGSN 616 is communicatively coupled with a PDF618 that provides authorization of media plane resources. PDF 618 may becommunicatively coupled with a CSCF 620.

CSCF 620 comprises various SIP servers or proxies that process SIPsignaling packets in IMS 620. CSCF 620 may include a P-CSCF, a S-CSCF,and an I-CSCF as is understood. HSS 640 stores user profiles thatspecify subscription-related information of authorized users,authenticates and authorizes users, and provides information about theuser's physical location. Various application servers 642 a-642 n mayhost and execute services and is interfaced with CSCF 620 via SIP.

The I-CSCF has an IP address that is published in DNS 672 thatfacilitates location of the I-CSCF by remote servers. Thus, the I-CSCFis used as a forwarding point for receipt of SIP packets within thedomain.

CSCF 620 is coupled with a BGCF 622 that comprises a SIP server thatprovides routing functionality based on telephone numbers. A MGCF 624performs call control protocol conversion between SIP and ISDN User Part(ISUP) and interfaces with a SGW 626 that itself interfaces with thesignaling plane of a circuit switched network, e.g., PSTN 630. A MGW 628interfaces with the media plane of PSTN 630 or another circuit switchednetwork. Resources of MGW 628 are controlled by MGCF 624. Fixed accessdevices, e.g., IP telephony devices 674 a-674 b, may connect with IMSnetwork via Internet 670 that is communicatively coupled with IMSnetwork 620 by way of border gateway 660.

Femtocell systems 650 a-650 c may include integrated BTS and BSCfunctions and may feature additional capabilities available in theprovided femtocell site coverage areas. Femtocell systems 650 a-650 cprovide an IP-accessible radio access network, are adapted for operationwith IMS 620, and provide radio link control functions. Femtocellsystems 650 a-650 c may be communicatively coupled with Internet 670 viaany variety of backhaul technologies, such as an 802.11x link, a 10/100BaseT LAN link, a T1/E1 Span or fiber, cable set top box, DSL modemconnected with a central office digital subscriber line accessmultiplexer, a very small aperture terminal (VSAT), or another suitablebackhaul infrastructure. In the illustrative example, femtocell systems650 a-650 c are each coupled with an IP backhaul access device 655, suchas an Ethernet cable or DSL router. For instance, femtocell systems 650a-650 c may be coupled with access node 655 via respective 10/100BaseTtwisted pair cables, Category 5 cabling, or other suitableinterconnection.

Each of femtocell systems 650 a-650 c provide a respective femtocellsite 651 a-651 c in which UEs 625 a-625 c may be providedtelecommunication services over an air interface. Femtocell systems 650a-650 c are communicatively coupled with one another via access device655. Femtocells 650 a-650 c deployed for conjunctively providing afemtocell service coverage area comprised of the collective femtocellsites 651 a-651 c are collectively referred to herein as a femtocellnetwork. In an embodiment, femtocell systems 650 a-650 c may exchangemessages with one another to facilitate handoff of a UE from onefemtocell to another, e.g., as UE 625 a moves out of the radio range ofa femtocell and into the radio range of another. In the depictedexample, the femtocell network provided by femtocell systems 650 a-650 cis at least partially overlapped by one or more macrocell sites 602a-602 c provisioned by macrocell BTSs 612 a-612 c. In such animplementation, femtocell systems 650 a-650 c may provide preference toanother femtocell for handoff of a UE thereto. In the event that anotherfemtocell is not available or is unsuitable for a handoff, the UE maythen be transferred to macrocellular coverage via a handoff to amacrocell BTS.

Each of femtocell system 650 a-650 c may include a respective SIPadapter that supports a SIP client pool and provides conversion of callset-up functions to SIP client set-up functions. Additionally, femtocellsystems 650 a-650 c include ESN screening to allow only designated UEsto access the femtocells thereby restricting access to authorized homeor small office UEs. For example, femtocell system 650 a may beconfigured with an ESN list 654 a that specifies ESNs of UEs authorizedto access femtocell system 650. In the illustrative example, ESNs of“ESN 1”-“ESN 3” are included in ESN list 654 a. Provisioning of ESN(s)may be made as part of an initial femtocell system 650 activation. Otherfemtocell systems 650 b-650 c may be similarly configured with an ESNlist including ESNs of UEs authorized to access the femtocell systemnetwork comprised of femtocell systems 650 a-650 c. In the illustrativeexample, femtocell systems 650 a-650 c are allocated a respective IPaddress of“66.249.73.42”, “66.249.73.43”, and “66.249.73.44”.

A private branch exchange (PBX) 656, e.g., an IP-PBX, may be deployedonsite at the SOHO that hosts the femtocell network comprising femtocellsystems 650 a-650 c. In the illustrative example, PBX 656 isinterconnected with access device 655. PBX 656 may provide telephoneexchange services for UEs authorized to access the femtocell network.

A BSM 678 may be deployed in Internet 670 and may be adapted tocommunicate with numerous femtocell systems and femtocell networks. BSM678 may provide various operations, maintenance, and managementfunctions to femtocell systems. BSM 678 may provide service provisioningof femtocell systems, e.g., by providing configuration downloads tofemtocell systems and preloading default configuration data forfemtocell systems distributed via sales channels. BSM 678 may providevarious support and maintenance features, such as alarm and periodicstatistics reporting, automatic remote software image distribution tofemtocell systems, provide upgrades and reconfigurations, and mayprovide remote access via Internet 670 for diagnostics and customersupport.

In accordance with an embodiment, mechanisms for call processing by afemtocell system in a network system are provided. In oneimplementation, the femtocell system includes a base transceiverstation, a transcoder, and a Session Initiation Protocol to InternetOperating System adapter. The femtocell system may receive an INVITEmessage from a core network for a call to be terminated with a userequipment serviced by the femtocell system. The femtocell system maypage the user equipment, and the Session Initiation Protocol to InternetOperating System adapter may transmit a connection request to thetranscoder which, in turn, opens a real time transport protocol portwith a service mode of receive only. An assignment request istransmitted from the Session Initiation Protocol to Internet OperatingSystem adapter to the base transceiver station. In response, the basetransceiver station transmits a channel assignment and a service connectmessage to the user equipment. In response to receiving a serviceconnect completion message, the femtocell system transmits a ringingindication to the core network and may modify the service mode of thetranscoder to send and receive. A bearer is then established for thecall, and an alert is transmitted to the user equipment. In response toreceiving a connect order from the user equipment, the call setup iscompleted by the femtocell system.

FIG. 7 is a flowchart 700 that depicts a femtocell system callprocessing routine that facilitates mobile terminated call processingimplemented in accordance with an embodiment. The call processingroutine may be implemented as a set of executable instructions tangiblyembodied on a computer-readable medium that are executable by aprocessing system, such as a femtocell system implemented in accordancewith disclosed embodiments.

The call processing routine is invoked (step 702), and the femtocellsystem receives a call origination for a call to be terminated with a UEserviced by the femtocell system from the IMS core network (step 704).The femtocell system then pages the UE (step 706) and creates aconnection (step 708).

The femtocell system may then create a connection for the IMS corenetwork (step 710). A channel assignment may then be issued to the UE(step 712), and the service connection is then completed between the UEand the femtocell system (step 714). The femtocell system then providesa ringing indication to the IMS core network (step 716), and a bearer isestablished for the call (step 718). The femtocell system issues analert to the UE (step 720), and a connection is established in responseto receipt of a connect order from the UE (step 722). The call setup isthen completed by the femtocell system (step 724), and the callprocessing routine cycle may then end (step 726).

FIGS. 8A and 8B show a diagrammatic representation of a signaling flow800 for a mobile terminated call processing routine implemented inaccordance with an embodiment. A call origination message, e.g., anINVITE message, is received from the IMS core network by the SIP to IOSadapter (SIA) of the femtocell system for a call to be terminated with aUE serviced by the femtocell system (step 802), and a trying response,e.g., a SIP 100 response, may be returned to the IMS core network by theSIA (step 804). A paging request may then be conveyed from the SIA tothe femtocell system's base transceiver station (BTS) (step 806). TheBTS, in turn, transmits a general page to the UE with which the call isto be terminated (step 808), and a page response is received by the BTStherefrom (step 810). The BTS may reply to the UE with anacknowledgement message (step 812).

The femtocell system SIA may then generate and transmit a createconnection (CRCX) message to the femtocell system transcoder (step 814),and the transcoder may reply to the SIA with a CRCX response, e.g., viaa session description protocol (SDP) message (step 816). At this point,RTP ports may be opened at the femtocell system transcoder with thespecified service mode set to receive only. The SIA may then transmit asession progress response, e.g., a SIP 183 response, to the IMS corenetwork (step 818), and the IMS core network may reply with aprovisional response acknowledgement (PRACK) (step 820). The SIA maythen reply with a successful response, e.g., a SIP 200 response (step822).

A paging response may be generated by the femtocell base transceiverstation and transmitted to the SIA (step 824), and the SIA may replywith an assignment request (step 826). In turn, the femtocell system BTSmay transmit a channel assignment to the UE (step 828) and mayadditionally transmit a base station acknowledgment message to the UE(step 830). The UE may then generate and transmit an acknowledgementmessage to the femtocell system BTS in response to receipt of thechannel assignment (step 832). A service connect may then be transmittedfrom the femtocell system BTS to the UE (step 834), and a serviceconnect completion response may be returned to the femtocell system BTSfrom the UE (step 836). An assignment completion may then be provided tothe femtocell system SIA 450 from the femtocell system BTS (step 838),and the SIA may transmit a ringing indication, e.g., a SIP 180 message,to the IMS core network (step 840) which replies with a provisionalresponse acknowledgement (step 842). The SIA, in turn, may transmit asuccessful response message, e.g., a SIP 200 response, to the IMS corenetwork (step 844).

The femtocell system SIA may then transmit a modify connection (MDCX)message to the transcoder (step 846) to modify the connection to sendand receive, and await a MDCX response therefrom (step 848). A bearerrequest may then be issued by the SIA and transmitted to the BTS (step850), and the SIA may then await receipt of a bearer response therefrom(step 852). An alert with information may then be transmitted from theSIA to the femtocell system base transceiver station (step 854).

An alert with information message may then be transmitted from thefemtocell system base transceiver station to the UE (step 856). An MSacknowledgement order may then be transmitted from the UE to the basetransceiver station (step 858) followed by a connect order (step 860).The base transceiver station, in turn, may transmit a connect message tothe SIA (step 862) and an acknowledgement message to the UE (step 864).In response to receipt of the connect message, the SIA may transmit asuccessful response message, e.g., a SIP 200 message (step 866), andawait receipt of an acknowledgment therefrom (step 868).

The transcoder may send an A2p message to the base transceiver station(step 870). Speech frames may then be transmitted to the UE (step 872)by the base transceiver station (step 872), and speech frames may belikewise received by the base transceiver station from the UE (step874). To this end, an A2p message may be transmitted to the transcoderfrom the base transceiver station (step 876). Exchanges may be madebetween the femtocell system and the IMS core network via a real timetransport (RTP) session (step 878).

As described, a communication system featuring an IP-based femtocellsystem for provisioning communication services to a user equipment isprovided. The femtocell system includes a base transceiver station, atranscoder, and a Session Initiation Protocol to Internet OperatingSystem adapter. The femtocell system may receive an INVITE message froma core network for a call to be terminated with a user equipmentserviced by the femtocell system. The femtocell system may page the userequipment, and the Session Initiation Protocol to Internet OperatingSystem adapter may transmit a connection request to the transcoderwhich, in turn, opens a real time transport protocol port with a servicemode of receive only. An assignment request is transmitted from theSession Initiation Protocol to Internet Operating System adapter to thebase transceiver station. In response, the base transceiver stationtransmits a channel assignment and a service connect message to the userequipment. In response to receiving a service connect completionmessage, the femtocell system transmits a ringing indication to the corenetwork and may modify the service mode of the transcoder to send andreceive. A bearer is then established for the call, and an alert istransmitted to the user equipment. In response to receiving a connectorder from the user equipment, the call setup is completed by thefemtocell system.

The flowchart of FIG. 7 depicts process serialization to facilitate anunderstanding of disclosed embodiments and is not necessarily indicativeof the serialization of the operations being performed. In variousembodiments, the processing steps described in FIG. 7 may be performedin varying order, and one or more depicted steps may be performed inparallel with other steps. Additionally, execution of some processingsteps of FIG. 7 may be excluded without departing from embodimentsdisclosed herein.

The illustrative block diagrams depict process steps or blocks that mayrepresent modules, segments, or portions of code that include one ormore executable instructions for implementing specific logical functionsor steps in the process. Although the particular examples illustratespecific process steps or procedures, many alternative implementationsare possible and may be made by simple design choice. Some process stepsmay be executed in different order from the specific description hereinbased on, for example, considerations of function, purpose, conformanceto standard, legacy structure, user interface design, and the like.

Aspects of the present invention may be implemented in software,hardware, firmware, or a combination thereof. The various elements ofthe system, either individually or in combination, may be implemented asa computer program product tangibly embodied in a machine-readablestorage device for execution by a processing unit. Various steps ofembodiments of the invention may be performed by a computer processorexecuting a program tangibly embodied on a computer-readable medium toperform functions by operating on input and generating output. Thecomputer-readable medium may be, for example, a memory, a transportablemedium such as a compact disk, a floppy disk, or a diskette, such that acomputer program embodying the aspects of the present invention can beloaded onto a computer. The computer program is not limited to anyparticular embodiment, and may, for example, be implemented in anoperating system, application program, foreground or background process,driver, network stack, or any combination thereof, executing on a singleprocessor or multiple processors. Additionally, various steps ofembodiments of the invention may provide one or more data structuresgenerated, produced, received, or otherwise implemented on acomputer-readable medium, such as a memory.

Although embodiments of the present invention have been illustrated inthe accompanied drawings and described in the foregoing description, itwill be understood that the invention is not limited to the embodimentsdisclosed, but is capable of numerous rearrangements, modifications, andsubstitutions without departing from the spirit of the invention as setforth and defined by the following claims. For example, the capabilitiesof the invention can be performed fully and/or partially by one or moreof the blocks, modules, processors or memories. Also, these capabilitiesmay be performed in the current manner or in a distributed manner andon, or via, any device able to provide and/or receive information.Further, although depicted in a particular manner, various modules orblocks may be repositioned without departing from the scope of thecurrent invention. Still further, although depicted in a particularmanner, a greater or lesser number of modules and connections can beutilized with the present invention in order to accomplish the presentinvention, to provide additional known features to the presentinvention, and/or to make the present invention more efficient. Also,the information sent between various modules can be sent between themodules via at least one of a data network, the Internet, an InternetProtocol network, a wireless source, and a wired source and viaplurality of protocols.

What is claimed is:
 1. A method, comprising: receiving, by a femtocell system, a call origination for a call to be terminated with a user equipment serviced by the femtocell system from a core network; transmitting, by a Session Initiation Protocol to Internet Operating System adapter of the femtocell system, a create connection message to a transcoder of the femtocell system; and performing, by the femtocell system, a service connection with the user equipment.
 2. The method of claim 1, wherein creating a connection for the core network comprises creating a connection for an Internet Protocol Multimedia Subsystem core network.
 3. The method of claim 1, comprising creating, by the femtocell system, a connection for the core network.
 4. The method of claim 1, comprising opening at least one real time transport protocol port at the transcoder in response to receiving the create connection message.
 5. The method of claim 4, wherein opening at least one real time transport protocol port further comprises specifying a service mode as receive only.
 6. The method of claim 1, comprising: transmitting, by a base transceiver station of the femtocell system, a channel assignment to the user equipment; and receiving, by the base transceiver station, a service connection completion message from the user equipment.
 7. The method of claim 6, comprising transmitting, by the femtocell system, a ringing indication to the core network in response to receipt of the service connect completion message.
 8. The method of claim 7, comprising modifying a connection service mode of a transcoder of the femtocell system to a send and receive mode in response to receipt of an acknowledgement to the ringing indication received from the core network.
 9. A non-transitory computer-readable medium having computer-executable instructions for execution by a processing system, the computer-readable medium comprising instructions that: receive, by a femtocell system, a call origination for a call to be terminated with a user equipment serviced by the femtocell system from a core network; transmit, by a Session Initiation Protocol to Internet Operating System adapter of the femtocell system, a create connection message to a transcoder of the femtocell system; and perform, by the femtocell system, a service connection with the user equipment.
 10. The non-transitory computer-readable medium of claim 9, comprising instructions that create, by the femtocell system, at least one of: a connection for the core network; and a connection for an Internet Protocol Multimedia Subsystem core network.
 11. The non-transitory computer-readable medium of claim 9, further comprising instructions that open at least one real time transport protocol port at the transcoder in response to receiving the create connection message.
 12. The non-transitory computer-readable medium of claim 11, wherein the instructions that open at least one real time transport protocol port further comprise instructions that specify a service mode as receive only.
 13. The non-transitory computer-readable medium of claim 9, further comprising instructions that: transmit, by a base transceiver station of the femtocell system, a channel assignment to the user equipment; and receive, by the base transceiver station, a service connection completion message from the user equipment.
 14. The non-transitory computer-readable medium of claim 13, further comprising instructions that transmit a ringing indication to the core network in response to receipt of the service connect completion message.
 15. The non-transitory computer-readable medium of claim 14, further comprising instructions that modify a connection service mode of a transcoder of the femtocell system to a send and receive mode in response to receipt of an acknowledgement to the ringing indication received from the core network.
 16. A system, comprising: a packet-switched network; an Internet Protocol Multimedia subsystem communicatively coupled with the packet-switched network; and a femtocell system communicatively coupled with the packet-switched network, wherein the femtocell system includes a base transceiver station, a transcoder, and a Session Initiation Protocol to Internet Operating System adapter, wherein the femtocell system receives a call origination for a call to be terminated with a user equipment serviced by the femtocell system from the Internet Protocol Multimedia subsystem, wherein the Session Initiation Protocol to Internet Operating System adapter transmits a create connection message to the transcoder and the transcoder opens at least one real time transport protocol port in response thereto, and wherein the femtocell system performs a service connection with the user equipment.
 17. The system of claim 16, wherein the transcoder specifies a service mode as receive only when the at least one real time transport protocol port is opened.
 18. The system of claim 16, wherein the base transceiver station transmits a channel assignment to the user equipment and receives a service connection completion message from the user equipment.
 19. The system of claim 18, wherein the femtocell system transmits a ringing indication to the Internet Protocol Multimedia subsystem in response to receiving the service connect completion message.
 20. The system of claim 19, wherein the transcoder modifies a connection service mode to a send and receive mode in response to receipt of an acknowledgement to the ringing indication received from the Internet Protocol Multimedia subsystem. 